As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
An information handling system may include one or more power supply units for providing electrical energy to components of the information handling system. Typically, a power supply unit is configured to operate from an input alternating current (AC) source of electrical energy, which the power supply unit converts to a direct current (DC) output. Thus, typically a power supply unit may include a rectifier and/or power factor correction stage to receive the input AC source and rectify the input AC waveform to charge a bulk capacitor to a desired voltage. A direct-current-to-direct-current (DC-DC) stage may convert the voltage on the bulk capacitor to a DC output voltage which may be used to power components of the information handling system.
A battery backup unit may be capable of, immediately after removal of the AC source to the power supply unit, providing electrical energy at its output for a period of time using stored charge within battery cells to provide an output direct-current voltage to allow for data to be saved or additional computing to take place. Such a period of time is limited, of course, as once the alternating current input is not available, the battery backup unit will discharge over time and the power supply unit will shutdown.
In many implementations, a chassis will include multiple information handling system sleds each with its own battery backup unit for providing power to on-sled loads of the information handling system (e.g., non-volatile memory, baseboard management controllers, remote access controllers, etc.) for a period of time as well as providing energy for powering chassis-level components such as chassis fans. Uneven sharing of current or power of the various battery backup units within a chassis can cause one battery backup unit to discharge more significantly than others. Thus, in a data-saving period required by components of an information handling system sled (e.g., non-volatile memory), the battery backup unit of such information handling system sled may drop below an expected state of charge, meaning such battery backup unit may not be able to support the system (e.g., supporting multiple alternating current power events).
Two approaches are typically used to solve current imbalance issues: active current sharing and passive current sharing. Active sharing often requires complicated communication, coordination, and control among battery backup units, which in turn requires complicated hardware and firmware design and support. Passive sharing is generally much simpler to implement, but traditional approaches to passive sharing are limited in effectiveness.
Any current sharing imbalance can create additional problems when an information handling system requires a higher amount of power neat the beginning of an alternating current power loss and lower power during a persistent memory save process. Such problems may be solved by battery backup units supporting higher charging capacities or the adjustment of maximum current settings, but such solutions are often costly or complex, and thus, undesirable.